Pulse-width-modulated signals (hereinafter PWM signals) are used in many applications in electrical engineering. These are signals having two allocated logical levels, or potentials. In general, relative to the time axis they may occur either in time-discrete or in time-continuous fashion. A main area of application of PWM signals is the representation of analog quantities in a digital system, as found for example in phase detectors in clock control loops or, in the present case, in controlling tasks using bridge circuits in power electronics.
European Patent No. EP 1 341 294 B1 describes an H-bridge circuit is known for use in a motor vehicle in which a predefined clocked course of a control voltage is set by switching more than one of the controllable switching arrangements. Here the switching arrangements are controlled such that in a first operating mode switching processes take place only in a first controllable switching means, whereas in a second operating mode switching processes take place only in a second controllable switching means, and a changeover is made periodically between the two operating modes, so that for a control voltage having a sign that remains constant, in alternating fashion a periodically clocked signal is produced at one of the two outputs and a constant signal is simultaneously produced at the other of the two outputs.